A. Field of the Invention
The present invention relates to a device for the virtual display of an image. More specifically the present invention relates to a device for the virtual display of moving images such as video, motion pictures and the like.
B. Discussion of the Prior Art
Devices are known for the production of a virtual image outside of such devices using an illuminated real object which is included fixedly or rotatably within the devices. In one such device, the virtual image is produced outside the housing by means of a fresnel lens which is arranged in the housing opening. The object can either be arranged lying directly opposite the fresnel lens inside th housing or staggered with respect to the fresnel lens, with the object then being depicted onto the fresnel lens by a suitable mirror arrangement. Such a three-dimensional image device is disclosed in European Patent No. EP-B1-0 410 968 by Raul Orlandi.
While suited for their intended purpose, a disadvantage of devices of this type is that only illuminated real objects can be depicted, which is complicated in practice and greatly restricts the use of this image device to objects which can be maintained in the housing. Whereas flat objects can be depicted with such a device with relatively no difficulty, three-dimensional distortions occur in the depicting of objects with greater three-dimensional depth. In addition, the observation of the image is substantially limited to a particular viewing axis which is determined by the foci of the fresnel lens. In other words, this known device suffers from a very tight viewing angle. To increase the viewing angle, a 3 to 1 size ratio is desired between the object and the lens. Thus, the object is generally 3 times smaller than the lens to increase the viewing angle.
The disadvantages set out above also apply to an alternative embodiment known in which the depiction of the real object takes place by means of a concave mirror arranged in the path of light rays and a partially translucent mirror, instead of with a fresnel lens. Finally, it is disadvantageous that an observer always has to look into the fresnel lens or into the concave mirror in order to observe the object, which is very disturbing due to the enlargement of the mirror image of the observer.